May, 1920] Descriptions of Diptera 273 



cheek as high as widest part of parafacial, with a series of bristles on 

 lower margin; third antennal segment 1.5 as long as second; arista 

 almost bare. Two or three pairs of closely placed acrostichals and some 

 interspersed hairs in front of suture; prealar half as long as the bristle 

 behind it; stemopleurals 2:2, the lower anterior one weak. Abdomen 

 subcylindrical, the tergites with strong apical bristles; hypopygium of 

 moderate size; fifth sternite with the processes chitinised, rounded at 

 apices, bare on apical half internally and with some fine hairs basally on 

 inner margins. Fore tibia with one anterodorsal and one posterior 

 bristle, apical posterior bristle long; fore tarsus a little longer than tibia,' 

 mid femur without strong bristles on antero ventral surface, the 

 posteroventral with a complete series; mid tibia with an anterodorsal 

 bristle and adjacent to it on the anterior surface a weak setula, one 

 posterodorsal and three posterior bristles; hind femur with a series of 

 long, irregular anteroventral bristles and a similar posteroventral series 

 which is interrupted before apex; hind tibia with two anteroventral, 

 three anterodorsal, and two posterodorsal bristles. Costal thorn 

 small; outer cross-vein slightly curved. Lower calyptra slightly 

 protruded. 



Length, 6 mm. 



Type, Katmai, Alaska, July, 1917. One male. 



Hylemyia Robineau Desvoidy. 



I have not used the subgeneric names given to segregates, 

 of this genus by recent European authors. Included in the 

 genus as recognized in this paper there are species which would 

 fall into the restricted subgenera Hylemyia and Phorbia. 



The following species are included in the key and recorded 

 for the first time for this continent: uniseriata Stein, fusciceps 

 Zetterstedt, and sepia Zetterstedt. Only in the case of the 

 last named have I any doubt as to the identification. The 

 species which has previously been identified by authors, includ- 

 ing myself, as fusciceps Zetterstedt is cilicrura Zetterstedt 

 according to Stein who has re-examined the types of the species. 



The key here presented is not designed for the identification 

 of all American species of the group as there are many more 

 species which are not included and are closely related to those 

 in the key. 



Some of the hypopygial drawings are not mentioned in the 

 text and reference must be made to the explanation of plates 

 for names. 



